Dyeing cotton or regenerated cellulose using sulfur dyes oxidized with aqueous sodium bromite solution

ABSTRACT

Method for dyeing cotton or regenerated cellulose textile fibers with sulfur dyes, comprising the steps of applying at least one sulfur dye in reduced (leuco) form to said fibers and subsequently oxidizing said dye by contacting it with an oxidizing solution comprising water and sodium bromite and having pH 7-12.

United States Patent Aspland 1 Feb. 13, 1973 [54] DYEING COTTON 0REGENERATED 1,905,346 4/1933 Dreyfus et al. ..8/64 Fryer et al. OXIDIZEDWITH AQUEOUS SODIUM OTHER PUBLICATIONS BROMITE SOLUTION John RichardAspland, Charlotte, NC.

Inventor:

Martin Marietta Corporation, New York, N.Y.

Filed; Jan. 25, 1971 Appl. No.: 109,593

Assignee:

US. Cl. ..8/37, 8/82, 8/51,

8/] Q, 8/] XA Int. Cl. ..C09b 49/00, D06p 1/30 Field of Search ..8/37,82, l 0,64

References Cited UNITED STATES PATENTS 10/1949 Mayhew ..8/37 X Knecht etal., Principles & Practice of Text. Print., 1952, p. 589-590 PrimaryExaminer-George F. Lesmes Assistant Examiner-Patricia C. Ives At!0rneylohn A. Crowley, Jr., Francis J. Mulligan, Jr. and Wilton Rankin [57]ABSTRACT 2 Claims, No Drawings DYEING COTTON OR REGENERATED CELLULOSEUSING SULFUR DYES OXIDIZED WITH AQUEOUS SODIUM BROMTTE SOLUTION Thepresent invention relates to a method for dyeing, and more particularlyto a method for dyeing textile fibers with sulfur dyes.

Generally speaking the present invention may be defined as in the methodfor dyeing cotton or regenerated cellulose textile fibers with sulfurdyes, comprising the steps of applying at least one sulfur dye inreduced (leuco) form to said fibers and subsequently oxidizing said dyeby contacting it with an aqueous solution of an oxidizing agent, theimprovement characterized in that said aqueous solution of an oxidizingagent comprises water and sodium bromite and has pH 7-12.

As used herein, the term sulfur dyes means those dyes which may beapplied in a reduced (leuco) state to cotton fibers from solutionscontaining sodium sulfide, or sodium hydrosulfide, or sodiumpolysulfide, and which dyes have affinity for cotton, and which dyes maybe subsequently oxidized on the fibers, and which dyes contain divalentsulfur in the form of thiol or alkali metal thiolate when in theirreduced state.

A number of oxidizing agents have been suggested for reduced sulfurdyes, but few are used on a large scale in commercial practice.

The most popular oxidizing agent for reduced sulfur dyes is sodiumbichromate mixed with acetic acid (called chrome and acid). Anotherpopular oxidizing agent for reduced sulfur dyes is hydrogen peroxide.Aqueous sodium chlorite has also been employed to a small degree incommercial practice as an oxidizing agent for reduced sulfur dyes.However, all of these prior art usages have disadvantages andlimitations, some of which will be described below. Certain of suchdisadvantages and limitations have, surprisingly, been overcome by themethod of the present invention.

The primary disadvantage of chrome and acid concerns stream pollution.Water pollution control authorities in some areas have already setstrict limits on the liquid waste effluent from chrome and acid dyeingwhich will be permitted to enter streams. To avoid very expensiveeffluent treatment systems, those in charge of a number of textilefinishing plants are actively seeking alternate oxidation systems.Relatively harmless effluent, largely dilute aqueous sodium bromide,results from the method of the present invention.

After reduced sulfur dye has been oxidized on cotton or regeneratedcellulose yarn, it is difficult to remove residual chrome and acid bywashing, and it is customary to soap the yarn at the boil during suchwashing. In the process of the present invention, soaping at the boiland excessive washing after oxidation are unnecessary, as the residuesresulting from the oxidation are water soluble salts. By avoidingsoaping at the boil, one source of yarn weight loss during dyeing iseliminated and processing cost is reduced.

The acid in chrome and acid causes undesirable liberation of H 8 duringthe oxidation step, and residual acid accelerates tendering of cotton onageing, while acid is not used in the oxidation step of the presentprocess, which is conducted under neutral or alkaline conditions.

The degree of wash fastness of cotton and regenerated cellulose dyeingsmade from sulfur dyes depends upon the particular sulfur dye employedand upon the oxidizing agent employed. Wash fastness of such dyeings isconsiderably less when hydrogen peroxide is used as the oxidant thanwhen chrome and acid is used as the oxidant. The wash fastness ofdyeings made by the process of the present invention varies fromacceptable to very good, depending upon the particular sulfur dyeemployed. Generally speaking, the wash fastness of dyeings made by theprocess of the present invention is about the same as the wash fastnessof dyeings resulting from hydrogen peroxide oxidation.

Hydrogen peroxide has the following three major disadvantages as anoxidizing agent for reduced sulfur dyes used on cotton and regeneratedcellulose textile fibers. Wash fastness of such dyeings is considerablyless than when chrome and acid is used as the oxidant; not all sulfurdyes, disadvantageously, such as those sulfur dyes made by sulfurizing4-hydroxydiphenylamine,

can be fully oxidized to stable shades with hydrogen peroxide; andconcentration of the peroxide in the oxidizing bath is both critical tothe fastness properties of the resulting dyeing and troublesome tocontrol, requiring frequent measurement of peroxide concentration Withmany sulfur dyes on cotton or regenerated textile fibers, chrome andacid oxidation results in dyeings having a harsh hand. This causesexcessive wearing of needles and fiber fracture during sewing andknitting, and necessitates use of lubricants during yarn and raw stockdyeing to soften the harsh yarn. Cotton and regenerated cellulosetextile fibers dyed by the present process with sulfur dyes have asurprisingly soft hand, thereby eliminating necessity for use of thelubricant.

Cotton and regenerated cellulose textile fibers dyed with sulfur dyes,wherein chrome and acid has been used as the oxidant, are not easilyrewettable, which necessitates use of wetting agents in any subsequentwet finishing operation, while fibers dyed by the present process areeasily rewettable in subsequent wet finishing operations, without theaid of wetting agents.

either by time consuming titrations or by use of an expensive machinefor measuring optical density and hence hydrogen peroxide concentrationin the ultra violet region of the spectrum. In contrast, all sulfur dyescan be oxidized to stable shades by the process of the presentinvention, even those made by sulfurizing 4-hydroxydiphenylamine.Generally speaking, and depending upon the particular sulfur dyesselected, the shades produced by sodium bromite oxidation indicate thatthe state of oxidation is either equal to that produced by chrome andacid oxidation, or that the state of oxidation is equal to or higherthan that produced by hydrogen peroxide. All reduced sulfur dyes areoxidized sufficiently with sodium bromite to produce adequately oxidizedand desirable dyeings.

The primary disadvantage of aqueous sodium chlorite as an oxidizingagent for leuco sulfur dyes applied to cotton and regenerated cellulosetextiles is that sodium chlorite simply will not oxidize many sulfurdyes to a commercially acceptable state, under conditions recommendedfor sodium chlorite, which are the same conditions recommended forsodium bromite herein. Some sulfur dyes bleed very badly after beingoxidized with sodium chlorite, or perhaps more precisely after beingpartially oxidized. Based on the dyeings which I have made with aqueoussodium chlorite, it is my opinion that aqueous sodium chlorite islittle, if any, superior to plain water as an oxidizing agent forreduced sulfur dyes on cotton and regenerated cellulose textile fibers.lndophenol sulfurized vat dyes, red-brown sulfur dyes made fromsulfurization of 4-hydroxydiphenylamine, and certain orange, blue andgreen sulfur dyes are not oxidized to a commercially acceptable state byaqueous sodium chlorite.

The following is a more detailed description of the present invention,and all parts herein are by weight unless otherwise specified.

The cotton and regenerated cellulose textile fibers which may be dyedaccording to the process of the present invention may be in any desiredform, such as knitted or woven fabric, yarn, ball warps, non-wovenfabric or raw stock.

The reduced (leuco) sulfur dye may be applied to the fibers in anydesired manner, such as by jig, pad, beck, roller, or package machine.

lf-desired the fibers having the dye thereon may optionally be batchedfor a period of time, steamed or dried to facilitate penetration of thedye into the fibers.

The fibers having the reduced sulfur dyestuff thereon are then contactedwith the aqueous oxidizing solution to fix the dyestuff, such as byimmersing the fibers in the oxidizing solution.

The neutral or alkaline aqueous oxidizing solution comprises water andsodium bromite, and has pH 7-12, and preferably pH9-l0. It will beunderstood by those familiar with bromite chemistry that at pH 7-9 smallamounts of sodium hypobromite will customarily be found in the aqueoussodium bromite. As aqueous sodium bromite solution is neutral, it willbe understood that small amounts of alkali, such as NaOH or Na,CO willbe present in aqueous sodium bromite solutions more alkaline than pH7.0. Accordingly, the aqueous oxidizing solution contains about -2percent alkali, depending upon its pH and upon the alkali selected.Enough sodium bromite should be employed to oxidize the dyestuff. incontinuous dyeing on padding equipment it is suggested that theconcentration of aqueous sodium bromite in the pad box be maintained at0.05-0.4 percent by weight, and preferably at about 0.1 percent byweight. In batch dyeing, it is suggested that the concentration ofsodium bromite be about 0.1 percent of the dry weight of the goods beingdyed. The aqueous oxidizing solution may also contain 0-30 percent of asimple electrolyte, such as NaCl, Na SO or MgSO, to inhibit bleeding ofdyestuff into the oxidizing solution. Use of the simple electrolytes isunnecessary in continuous pad dyeing, but may be advantageous in somebatch dyeing processes. If desired, the oxidizing bath may contain otherconventional additives such as non-ionic or anionic surface activeagent, e.g., a fiber wetting agent. Excessive amounts of sodium bromitemay decrease wash fastness of the dyeing. If the oxidizing solution isto be stored for several days, it is suggested that it be stabilized byraising the alkalinity to pH 10 or above with an alkali such as NaOH.

Accordingly, the aqueous solution of sodium bromite used in continuouspad dyeing by the process of the present invention may comprise, byweight, 0.05-0.4

percent sodium bromite, 030% NaCl, Na SO or Mg- SO,, O-2 percent alkali,67.6-99.95 percent water, and have pH 7-12. In batch dyeing, theconcentration of sodium bromite will be less.

The oxidizing solution may be at ambient temperature to 160 F. when itcontacts the leuco dyestuff. Aqueous sodium bromite at ambienttemperature readily oxidizes sulfur dyes, but the oxidation rateincreases with temperature increase. Oxidation proceeds very rapidly incontinuous dyeing, and is essentially complete when the dyestuff andaqueous sodium bromite have been in contact about 30 seconds, based on0.1 percent sodium bromite concentration at ambient temperature. Inbatch dyeing, the fabric having thereon dyestuff will customarily remainin the 0.1 percent by weight of goods aqueous sodium bromite about 10-15minutes to achieve the desired oxidation.

After oxidation of the dyestuff, the fibers may be washed and dried inconventional manner.

The following are illustrative examples of embodiments of the presentinvention, in which all parts and percentages are by weight unlessotherwise specified. References in the examples to C. 1. names andnumbers for sulfur dyes are to COLOUR INDEX, Second Edition, Supplement1963, published by The Society of Dyers and Colourists, Yorkshire,England.

EXAMPLE 1 A dye solution is made by reducing 1 oz. coppertetra-(4)-thiocyanophthalocyanine (U.S. Pat. No. 2,342,662) with aqueousNa S and diluting to 1 gallon with water. To woven cotton shirtingweighing 4 oz/sq. yard is applied, by padding, the dye solution at F.,whereafter the fabric is squeezed to permit 60 percent wet-pick-up basedon fabric weight. The fabric is steamed at 230 F. for 1 minute; passedthrough three wash boxes containing water and equipped with nip rollers;immersed for 30 seconds in an aqueous oxidizing solution at roomtemperature containing 0.1 percent sodium bromite and adjusted to pH 10with NaOH; rinsed by passing through 3 wash boxes containing warm water;and dried. A brilliant green dyeing results.

When 0.1 percent sodium chlorite is substituted for the 0.1 percentsodium bromite used in Example 1, a dull greyish-green dyeing results.

EXAMPLE 2 This example is the same as Example 1 above, except that a dyesolution consisting of 20 oz. SODYESUL Liquid Black 4GCF (20 percentaqueous prereduced C. l. Leuco Sulfur Black 1, C. I. No. 53185) pergallon of water is substituted for the dye used in Example 1.

A black dyeing very similar to that obtained with chrome and acidoxidation, except having better rewettability, results. When sodiumchlorite is substituted for sodium bromite in the process of Example 2,a yellower and duller dyeing than the Example 2 dyeing results.

EXAMPLE 3 This example is the same as Example 1 above, except that 1 oz.C. I. Sulphur Brown 52 powder (C. I. No. 53320), calculated as pure dye,is substituted for the copper tetra-(4)-thiocyanophthalocyanine used inExample l, and except that the sodium bromite solution is at 160 F. Theresulting dyeing is reddish orange.

When sodium chlorite is substituted for the sodium bromite used inExample 3, the resulting dyeing is dull brick red.

EXAMPLE 4 This example is the same as Example 1 above, except that 1 oz.C. l. Sulphur Red powder (C. I. No. 53228), calculated as pure dye, issubstituted for the copper tetra-(4)-thiocyanophthalocyanine usedin-Example l, and except the concentration of sodium bromite isincreased from 0.1 to 0.4 percent. The resulting dyeing is a fullydeveloped red-brown dyeing.

When sodium chlorite is substituted for the sodium bromite used inExample 1, there is insufficient color development on the resultingdyeing, and the resulting dyeing bleeds considerably on washing.

EXAMPLE 5 This example is the same as Example 1 above, except that 1 oz.C. l. Sulphur Blue 13 powder (C. I. No. 53450), calculated as pure dye,is substituted for the copper tetra-(4)-thiocyanophthalocyanine used inExample l, and except that the sodium bromite solution is adjusted to pH12 with NaOH.

A bright blue dyeing results. The resulting dyeing is brighter thanthose obtained with chrome and acid oxidation, but slightly inferior inwash fastness to chrome and acid dyeing.

lf sodium chlorite is substituted for the sodium bromite used in theExample 5 dyeing, the resulting blue dyeing is not fully developed.

EXAMPLE 6 This example is the same as Example 1 above, except that oz. 6percent aqueous pre-reduced C. l. Leuco Sulphur Green 2 dye (C. I. No.53571) per gallon of water is substituted for the dye solution used inExample 1; except that NaOH is omitted from the sodium bromite solution,which has pH 7; except that regenerated cellulose rayon fabric weighing3 oz./sq. yard is substituted for the cotton fabric; and except that thetemperature of the sodium bromite solution is increased to F.

A green dyeing results.

EXAMPLE 7 This example is the same as Example 1 above, except that 1 oz.C. I. Sulphur Brown I dye powder (C. I. No. 53000), calculated as puredye, is substituted for the copper tetra-(4)-thiocyanophthalocyanineused in Example l; except that the sodium bromite concentration isreduced to 0.05 percent; and except that woven regenerated celluloserayon fabric weighing 3 oz./sq. yard is substituted for the cottonfabric used in Example l.

A chocolate brown dyeing results, similar in shade to that obtained fromchrome and acid oxidation but with slightly inferior wash fastnessthereto.

What is claimed is:

1. In the method for dyeing cotton or regenerated cellulose textilefibers with sulfur dyes, comprising the stepspf applying at least onesulfur dye in reduced form to said ti ers and subsequently oxi izingsaid dye by Notice of Adverse Decision in Interference In InterferenceNo. 98,460, involving Patent No. 3,716,325, J. R. Aspland, DYEING COTTONOR REGENERATED CELLULOSE USING SUL- F UR DYES OXIDIZED WITH AQUEOUSSODIUM BROMITE SOLU- TION, final judgment adverses to the patentee wasrendered June 29, 1976, as

to claims 1 and 2.

[Ofii'cz'al Gazette November 30, 1.976.]

1. In the method for dyeing cotton or regenerated cellulose textilefibers with sulfur dyes, comprising the steps of applying at least onesulfur dye in reduced form to said fibers and subsequently oxidizingsaid dye by contacting it with an aqueous solution of an oxidizingagent, the improvement wherein said aqueous solution of an oxidizingagent comprises, by weight, 0.05-0.4 percent sodium bromite, 0-30% NaCl,Na2SO4, or MgSO4, 0-2 percent alkali, and 67.6-99.95 percent water, andhas pH 7-12.